B&S 17.5 mod.31C707

oldriver

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Hello and thanks in advance for any advice.Inherited low hour mower after it sat for couple of years.Engine will not make complete revolution.Stops in bind around 300 degrees both directions.Evidently at time for exhaust push rod actuation as it never moves.Exhaust valve moves by hand and intake works normally.Search finds mentions of object introduced to intake.Carb. was left off for some time,but i see no evidence of anything inside.Belts are not stuck.Any advice toward logical diagnosis appreciated.
 
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Valves need adjusting I do mine at 4 thousands for both ~!~! If that doesn't do the trick and the valves were set correctly then your compression release could be shot........

Boo will come along and post a link to a funny but informative video......
 

oldriver

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Engine will not not rotate by hand even with spark plug removed.Valves not stuck.I guess could be acr related as i don't have full grasp of how that works yet.Thinking i should just try to remove exhaust push rod but wanted to see if i was missing something simpler.Thanks for your view and reply
 
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Oh I thought you meant it was hard to turn on the comp stroke.... So you saying it won't turn at all once it gets to that spot ???

Wow something came loose inside then...... Take the valve cover off and check to see if both your pushrods are there ~!~!
 

oldriver

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Yes both pushrods present.Engine was running when last parked.
 
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If your sparkplug is removed then you should be able to turn that engine over and over with the starter easily. No compression like that....

Unless your belt is tight and jamming on something..... Try looking at your belts under your mower You will have a drive belt and a blade belt ...........

Let us know Mon Ami ~!~!
 

Boobala

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As Bo said, with plug removed, and belts off engine pulley, engine should be able to spin with no effort, before going in the BOTTOM end I'd check under the flywheel for something stuck to the flywheel magnet, I once saw a similar case where there was a small bolt that somehow got stuck on the inner side of the flywheel and did the exact same thing, engine locked up, if not that, then remove the push-rods and see what happens, you mentioned something MAY have been in the engine intake, might want to pull the head and see if you have something on top of the piston, easier pulling the head, than the whole engine and bottom end ........... keep us informed.
 

oldriver

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Thanks for reply.Guess pulling pushrod is best next step.Can't see it being under flywheel as i think i would hear it but will check.If something was in cylinder seems like it would be more of a dead stop.When it stops it goes into a bind and has to be forced back the other way,then moves freely about 300 deg. where it meets same binding stop.
 

Boobala

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Thanks for reply.Guess pulling pushrod is best next step.Can't see it being under flywheel as i think i would hear it but will check.If something was in cylinder seems like it would be more of a dead stop.When it stops it goes into a bind and has to be forced back the other way,then moves freely about 300 deg. where it meets same binding stop.

Whatever the case ...... it don't look healthy, TAKE PIC'S during dis-assembly if you go into it, ... ESPECIALLY the carb linkages !!!
 
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Driver I have one more question for you......

You keep saying it gets into a bind even with the plug out and you mention you can turn it one way.... Then you turn it the other way and binds again....

Here is the question ....... When it gets in a bind ... Does that mean a dead stop bind and you cannot move it anymore??

If that is the case then your connecting rod is broke inside the engine or something else came loose like I said in post #4.

You should have syncro balancer in that engine..... Maybe that came loose..... It does happen....It's not common, but it's not rare either......

If it does spin over 4 or 5 times total 360 degrees, then that's not the case....

Let us know Mon Ami ~!~! We want to solve your issue ~!~!
 
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